Thank you for your valuable feedback.
If I understand correctly, you're talking about two issues. One is about 'before-edge' and 'after-edge'. As you pointed out, they are gone in the current WD, so I don't think we need to worry about that.
I'm more curious about the other one you mentioned:
> I have a very good feeling in the behavior that the
> underline position with "auto" makes the position a
> little lower than that with "alphabetic" in the horizontal
> writing mode
Although current WD defines 'auto' as UA dependent, I think this should be added as an example so that implementers know how to implement a good underline rendering method for CJK.
Can you please share with us how you implement "make the position a little lower" in AH Formatter? Do you use the same position as "under", information from OpenType font, or any heuristic value?
Regards,
Koji
-----Original Message-----
From: www-style-request@w3.org [mailto:www-style-request@w3.org] On Behalf Of Keiko Hiraide
Sent: Monday, December 20, 2010 6:32 PM
To: www-style@w3.org
Subject: [CSS3 Text] text-underline-position
Hello,
After formatting a sample of text-under-position with AH Formatter, I have a very good feeling in the behavior that the underline position with "auto"
makes the position a little lower than that with "alphabetic" in the horizontal writing mode. However, because "before-edge" and "after edge" are drawn outside of "line-height", it moves to the next line, then it is not easy to recognize to which line under line is drawn. Will the interpretation that "before-edge"
and "after-edge" are drawn inside of "line-height" be impossible?
Also, in vertical writing mode, "auto" is being interpreted as "before-edge", which is OK. But the underline overflows to the next line similarly in horizontal writing mode. Will the interpretation that "before-edge" and "after-edge" are drawn inside of "line-height" be unskillful?
Here is an example of text-underline-position formatted by AH Formatter.
http://www.antenna.co.jp/XML/img/underline.jpg
The current AH Formatter V5.2 adopts the values of 'before-edge' and 'after-edge'
according to;
http://www.w3.org/TR/2003/CR-css3-text-20030514/#text-underline-position
However, according to the recent spec;
http://www.w3.org/TR/css3-text/#text-underline-position/
I understand if 'over' and 'under' are adopted and refer to 'em-box', the problem I pointed out will not be an issue.
If the values of 'before-edge' and 'after-edge' remain in the future, I suggest it better to add 'inside of ' as follows.
before-edge
the underline, if set, is aligned inside of 'before-edge' of the line box.
after-edge
the underline, if set, is aligned inside of 'after-edge'
baseline of the line box....
I think the underline of 'before-edge' and 'after-edge' should be processed inside of line-height.
Thank you,
Keiko Hiraide
Antenna House, Inc.
Web: www.antennahouse.com